IDD NEWSLETTER NOVEMBER 2014 IODINE DEFICIENCY IN ARGENTINA 5

Iodine deficiency in pregnant women in Argentina

The Northwest Region of Argentina, including the provinces of Jujuy, Salta, Catamarca, Tucuman, and Santiago del Estero (Fig. 1), has long been recognized as an iodine deficient area. The iodization of salt for human consumption in Argentina was legislated in 1967 and implemented in 1970. However, the quality of iodized salt was not monitored, and the ThyroMobil study in 1998 showed that only about 70% of the salt was adequately iodized (1). In addition, there is no official data on the current status of iodine nutrition in Argentina. Regional surveys conducted by the Argentinian Federation of Endocrine Societies (FASEN) in 1999–2008 (2) have shown low urinary iodine concentration (UIC) and high rates of endemic goiter (>5%) in school-age children (SAC) main-ly in the Northern provinces. Moreover, national screening for congenital hypothy-roidism found that the prevalence of TSH levels greater than 5 µU/mL was 6.3% in Salta (3). The National Centre for Nutritional Investigation in Salta recently measured UICs in pregnant women and SAC, and the household consumption and quality of iodized salt in the Northwest Region (4).

Subjects and methods The study included 627 pregnant women in the first trimester from the five provinces of the Northwest Region, recruited from Public Health Service ambulatory centers in 2011–2012. Spot urine samples were colle-cted for iodine analysis, and 614 salt samples were collected from households. In a sepa-rate study, the UIC was analyzed in a group of 3011 school-age children.

Results The overall median UIC in SAC was 117 µg/L (a median of 100 µg/L indicates adequate iodine nutrition in a population), but in the

province of Salta it was only 78 µg/L. The median UIC in pregnant women was 119 µg/L overall and was insufficient in each of the provinces (Table 1).

There were 36 brands of salt in the North-west Region: 20 from regional and 16 from large national producers. The mean iodine content in the salt varied from 14 ± 13 ppm

in Jujuy to 37 ± 7 ppm in Tucuman (Table 2). Overall, 70.7% of the salt was adequately iodized, but the quality of iodized salt from large producers was signi-ficantly higher (98% samples had adequate iodine levels) than from regional producers (59% had adequate iodine). Nearly 10% of the samples from regional producers contained no iodine at all.

Preventing iodine deficiency in pregnancy leads to higher IQ in children

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Sonia López-Linares Centro Nacional de Investigaciones Nutricionales-ANLIS, Salta, Argentina and Eduardo A. Pretell IGN Regional Coordinator for the Americas

TABLE 1 Urinary iodine concentration in school-age children and pregnant women in Northwest Argentina

Province SAC Pregnant women n Median UIC n Median UIC µg/L µg/L

Tucuman 734 117 221 134

Santiago del Estero 783 136 42 139

Catamarca 609 122 25 136

Salta 433 78 231 111

Jujuy 452 106 93 104

All Region 3011 117 612 119

6 IDD NEWSLETTER NOVEMBER 2014 IODINE DEFICIENCY IN ARGENTINA

CommentsAlthough the overall median UIC in SAC suggests adequate iodine nutrition in Northwest Argentina, the low median UIC in Salta is caused by the consumption of inadequately iodized salt, which requires close monitoring. In addition, widespread iodine deficiency in pregnant women may increase the risk of poor fetal brain deve-lopment. Based on these data, about 71,200 newborns in the region in 2010 were at risk of cognitive impairment due to in utero iodine deficiency. This risk may also be present in other regions of the country, as iodine deficiency in pregnant women was recently reported in Córdoba (5) and Buenos Aires (6). Since much of the regionally produ-ced iodized salt consumed in the Northwest Region is of poor quality, it is unlikely to cover the increased need for iodine during pregnancy. Iodine status in pregnancy is poorest in the provinces with the highest consumption of regionally produced, ina-dequately iodized salt, such as Salta and Jujuy (Table 3). In Santiago del Estero and Catamarca, the salt originates almost exclusively from large producers, but in the other three provinces, more than 50% of consumption is covered by regionally iodized salt. Across these provinces, there is a direct correlation between the medi-an UIC and the mean iodine level in salt. Thus, Tucuman, Santiago del Estero, and Catamarca have the highest median UIC

and salt iodine levels, while Salta and Jujuy have the lowest. This study also reveals the inadequate

efforts to moni-tor the quality of iodized salt in Argentina since the ThyroMobil study 15 years ago: the proporti-on of adequately iodized salt has remained unchan-ged at about 70%. This is mainly a consequence of the low priority assigned to iodine deficiency in the country, the absence of an offi-cial IDD control

program, and the lack of surveillance and monitoring of the iodized salt and iodine nutrition. In a recent sub-regional workshop, organized joint-ly by ICCIDD Global Network and UNICEF as part of the Sustainable Elimination of Iodine Deficiency Disorders in Latin America (STELA) project (see page 7 in this issue), Argentina discussed its IDD situation with other countries in the region, exchanged experiences, and reviewed the latest scienti-fic advances in the field. It formulated a national Work Plan on IDD control, and its implementation will now be pursued. The plan stresses the need for a national IDD control program, universal salt iodization and quality assurance of iodized salt as the first steps. It is of parti-cular importance to ensure adequate iodine intake in pregnant and lactating women, and in children <2 years of age, to prevent the

risk of permanent cognitive impairment caused by iodine deficiency.

Bibliography1. Pretell EA, et al., Iodine nutrition improves in Latin America. Thyroid. 2004; 14:595–6042. Pretell E and Niepomniszcze H. Iodine deficiency persists in Northern Argentina. IDD Newsletter. 2009; 2:8–9 3. Hospital Público Materno Infantil de Salta. TSH Neonatal como herramienta para monitorear la defi-ciencia de yodo. MSP. Informe No. 20104. Sonia López Linares, et al. Monitoreo de los Desórdenes por Deficiencia de Iodo en embarazadas de la Región NOA. Rev. Argent. Salud Pública. 2012; (3)13 5. Szafryk-Mereshian P, et al. Adaptación al Aporte Nutricional de Yodo en Embarazadas de la ciudad de Córdoba. Rev. Argent. Endocrinol. Metab. 2004; 41:58 6. Prieto L, et al. Determinación de yoduria en la población materno infantil de la ciudad de Buenos Aires. Rev. Argent. Endocrinol. Metab. 2005;

42:131–136

TABLE 2 Iodine content of salt consumed in households across Northwest Argentina

Province n Mean ± SD (ppm) RangeTucuman 221 37 ± 7 7–71

Santiago del Estero 42 32 ± 7 17–49

Catamarca 21 31 ± 8 20–59

Salta 234 17 ± 11 0–60

Jujuy 96 14 ± 13 1–51

TABLE 3 Percent distribution of iodized salt consumption according to type of producer

Province National Regional Unknown (n=210) (n=340) (n=64) % % %Tucuman 39 60 1

Santiago del Estero 100 0 0

Catamarca 91 0 9

Salta 15 67 18

Jujuy 27 54 19

All Region 34 56 10

n = number of salt samples

F IGURE 1 Map of Argentina showing the NorthwestRegion in purple